1. Field of the Invention
The present invention relates to an orally administered adsorbent, a method of producing the same, and a drug produced by using the same, and more particularly to an orally administered adsorbent comprising spherical particles of activated carbon obtained by using spherical particles of furfuryl alcohol resin, a method of advantageously producing the same, and a drug produced by using the same.
2. Discussion of Related Art
Conventionally, an orally administered adsorbent is orally administered to a patient of a renal disease, for example, in order to adsorb uremic toxins and prevent a progress of renal failure. The orally administered adsorbent has been produced by using pitch materials. However, there is a problem that the conventional orally administered adsorbent derived from the pitch materials adsorbs digestive enzymes together with uremic toxins. Therefore, there have been recently developed techniques for producing orally administered adsorbents which selectively adsorb uremic toxins having a relatively small molecular size, such as β-aminoisobutyric acid, such that the adsorbents are produced by using a thermosetting resin such as a phenolic resin and an ion-exchange resin (Patent Documents 1-5). Such adsorbents are commercially available.
However, the conventional orally administered adsorbents are still insufficient in their ability of adsorption of major constituents of uremic toxins, and their ability of adsorption of indoxylsulfuric acid (most widely used uremia-related marker), in particular, is not clarified. “4th Generic Drug Quality Information Review Conference Material 4-1-2” (Non-Patent Document 1) discloses that a commercially available orally administered adsorbent obtained by using a thermosetting resin (phenolic resin) has an insufficient ability of adsorption of indoxylsulfuric acid, and indicates a problem that the ability of adsorption of indoxylsulfuric acid has to be improved.
Further, the orally administered adsorbents proposed in the above-indicated Patent Documents 1-5 are produced by using a petrochemical resource as their starting materials, and therefore cannot sufficiently meet a recent requirement for reducing carbon dioxide emissions.